I expect Belarus to be the flashpoint, not Ukraine. This gets the Russians right up to the Polish border.
Russia is already on the Polish border in occupied Koenigsberg and nothing’s happened. I would hope the Russians have the sense to avoid hostilities with NATO.
If not, then that will be the end of Russia.
Lukashenko’s plane has not returned to Minsk. It arrived in Moscow on May 24th and is still there.